Electric pressing irons



April 1, 1958 A. NEGROMANTI ELECTRIC PRESSING IRONS 2 Sheets-Sheet 1 Filed May 51, 1955 may v E April 1, 1958 A. NEGROMANT! 7 2,829,232

ELECTRIC PRESSING IRONS Filed May 31, 1955 2 Sheets-Sheet 2 azzzi/ ELECTRIC PRESSING IRUNS Antonio Negromanti, Milan, Italy Application May 31, 1955, Serial No. 512,093

Claims priority, application Great Britain June 3, 1954 8 (Ilaims. (Cl. 219-25) The object of the present invention is to provide an electric smoothing iron capable of being adapted to any domestic voltage in use, wherein the temperature can be regulated at will, the thermal efliciency is high, and the basic consumption of energy is low; an iron that will lend itself readily to rapid and economical mass production, will obviate shocks, and the dangers of erroneous connection, and also the risk of disturbing radio-reception, and which will be easy and practical to use, will give faultless service for a long time, and will be of pleasing appearance.

With the above purposes in view, a work-plate of bronze is employed which is capable of resisting shocks, is of high thermal capacity, and is a good conductor of heat. This plate has a marked reduction in breadth towards the rear, to enable it to be used in both directions, either fowards or backwards, thus obviating the need for changing hands.

Upon the inner face of this plate are formed grooves having the form indicated in the accompanying drawings, thereby permitting the use of variously arranged heating circuits, and a uniform distribution of heat. The heating resistances are according to the invention seated freely in the said grooves, without being secured thereto, thus permitting easy and rapid assembling and exchanging.

Such heating circuits may be produced by machine, in substantial lengths, by winding helically upon a flexible and incom'bustible core a previously insulated resistance wire, the whole being subsequently covered with likewise flexible and incombustible threads or filaments, of glass or asbestos for example.

According to the invention the terminals of the heating circuits are resiliently mounted upon a support of electrically insulating and heat-resisting material, such for example as steatite.

The body of the flat-iron consists of a block of heatproof material, of high thermal insulating power and great mechanical strength, besides being electrically insulating, such for instance as porous cement, in order to reduce to a minimum the losses of heat and to moderate its surface temperature, so as to allow of the use of non-metallic casing or shell members. This yields the possibility of using casing or shell members with an associated handle all in one piece, produced by stamping or by the injection of synthetic resins, such for example nylon or as the substances marketed under the registered trademarks Bakelite or Teflon. Hence, the utmost simplicity and rapidity of construction and assemblage are obtained, with aesthetic colours and effects never attained hitherto.

The temperature-regulating members and the clamps for anchoring the current-supply wires are mounted upon a plate placed upon a substantially vertical area at the back of the handle and of the casing, an area which I is hollow inwards.

This plate is registered in its correct position upon 2,829,232 Patented Apr. 1, 1958 an undercut peripheral cavity with slideways, in such a way as to transmit the current to the heating circuits by simply pressing contacts on to corresponding spring terminal clamps. The clamps for anchoring the currentsupply wires are placed on the outside and in the working direction, to obviate the harmful bendings to which the frequent breakages of such wires are due.

This also renders it necessary to keep the iron in a horizontal position during its idle periods, and therefore to make use of a thermally insulating iron-stand in order to obviate needless dissipation of heat.

The finger-rests have been designed in the most appropriate form and position with the help of a plastic substance such as modeling clay or Plasticine, by marking the impression of the thumb in its natural working position, whether for a person using his right hand or for those who use the left hand. This is of great practical importance, particularly for professional laundry ironers, in order to give the hand a restful position.

As will be seen, an electric pressing iron thus designed may be reduced to six essential parts, namely: a body, of heat-insulating material; a shell and associated handle, of a non-metallic nature; a work plate; the heating circuits, with the associated resilient terminal clamps; a support for the said resilient terminals; a supporting plate for the regulating members; and the anchoring clamps for the current-supply wires, leading to the current plug.

These parts, as will be realised, are quite independent of one another, and may be manufactured on mass-production lines separately from one another, in such a way that a single screw Will be sufficient to hold them together, thereby yielding great simplicity. andrapidity of construction and assembly, with a substantial economy of time and money.

A thermostatic valve is employcd,the bimetallicjsensitive member of which must be able to control simultaneously the temperature of two heating circuits, either whether in series or in parallel with one another, This valve is capable of effecting the continuous automatic cleaning of the contact surfaces, and the instantaneous interruption of the current for the purpose of obviating sparking, which would be liable to disturb-radioqecep tion.

The current plug is designed so as to-effect byfitself the supplying of current to the heating circuitseitherin series or in parallel with one another, by .means .of a fuse readily exchangeable from the exteriorin .:order to obviate any risk in the event of an erroneous insertion.

A preferred form of construction of the present invention is illustrated merely by way of example in :the accompanying drawings, in which:

Figure 1 shows the smoothing ironv partly in sideelevation and partly in medial longitudinal section;

Figure 2 is an outside view of the iron from. the rear;

Figure 3 shows the work-plate as seen fronmabove, with the heating circuits and the associated resilient terminals on their steatite support;

Figure 4 shows in central section a spring terminal of the heating circuits upon its associated steatite support;

Figure 5 shows the thermostatic valve in central longitudinal section;

Figure 6 shows the same valve as seen from -the=front,

on the side of the sensitive bi-metallic member;

Figure 7 shows the current plug in central section in the plane of the plug pins, in the position forfeeding the two heating circuits in series;

Figure 8 is an outside view of the same from above on the plane of the plug pins;

Figure 9 shows the current plug in centralsection in the plane of the plug pins in the position'for feeding the two heating circuits in parallel; and

current plug as illustrated by way of example in Figure 1.

'Figure 10 is an outside view of this current plug from above on the plane of the plug pins.

In these drawings, It denotes the work-plate, upon the inside surface of which are formed channels 2 and 3,.in which are freely lodged the two heating circuits 4 and 5,

of refractory and heat-insulating material 13, such as porous cement.

In the rear portion of the handle 12 and of the casing I 11a cavity 14 is provided, which is sealed in a fluidtight manner from the exterior by a plate 15 of Bakelite or the like, which is held in its place by a peripheral undercut groove with slideways 16. Upon this plate 15 are mounted clamps 17, 1S and 19 for anchoring the currentsupply wires leading to a pin plug 20. The clamps 17 and 19, through the medium of associated struts 21 and 22, are connected with contact brushes 21 and 22, which are adapted to bear against the spring clamps 6 and 9.

The clamp 18 is connected by means of a strut 23 with a silver disc 24, against which contacts 25 and 26 can be caused to hear, these contacts being connected by means of two flexible cables 27 and 28 to two contact brushes 29 and 30, which in their turn come in contact with the spring clamps 7 and 8 respectively.

' in parallel with one another.

It will be obvious that the fuse 31 will have to be designed for the maximum current compatible with the feeding of the heating circuits in parallel, as indicated in Figures 9 and 10. It is obvious from Figure 9 that the fuse will be readily exchangeable merely by removing the plug pin associated with the screw clamp 18.

The contacts 25 and 26 are mounted on a metal plate 32 and electrically insulated therefrom. The plate 32 is fulcrumed on a bracket 33. A spring 34 controlled by a bi-metallic strip 35 urges the plate 32 and therefore the contacts 25 and 26, against the disc 24, which is adjustable in height by means of a screw stem 36, which can be rotated by means of a handwheel 37.

The bi-metallic strip 35, fixed by a screw 33 to the plate 15, and placed for example with the face that has the higher coefiicient of expansion turned towards the disc 24, will move away from the said disc, as the result of a rise of temperature, so far as to determine a quick upward swing of the plate 32, thereby producing a sudden interruption of the current.

It will be obvious that the temperature of interruption of the current will depend upon the position of the disc 24, whether the heating circuits are in series or in parallel with one another. It will therefore be possible to arrange matters in such a way that for one complete revolution of the hand-wheel 37, and therefore of the disc 24, there will correspond the entire range of temperatures required for the ironing of rayon, silk, wool, cotton or linen extending from about 120 to 160 C.

As shown in Figure 4, each of the circuits 4 and consists of a flexible and incombustible core 39, upon which -is helically wound mechanically and in considerable The spring clamps 6, 7, 3 and 9 to which the ends of the resistance wires 40 of the circuits 4 and 5 are secured each consist, as shown in Figure 4, of a terminal sleeve urging the sleeve upwards. The screws 42 of the assesses 43 slidably accommodated in the steatite support 10, a .screw 42 fastening the wire to the sleeve, and a spring springs clamps 6, 7, 8 and 9 bear against the contact brushes 21', 29, 30 and 22' respectively of the insulating plate 15.

The entire assemblage so far described is mounted and held together by a single screw 45, secured to the plate 1, and a circular nut 46, which is tightened with a forked key engaging in holes 47 and 43.

Upon such a nut may be engraved thernakers trademark, the permissible limits of voltage, the energy consumption in watts, and any other useful indications.

49 is a disc of heat-insulating material, such as asbestos, to prevent the temperature of the plate 1 being transmitted to the handle 12.

I claim:

1. A pressing iron, comprising: a sole-plate formed with grooves in its inner surface, a casing, including a handle, mounted upon the sole-plate, a plate of electrically insulating and heat-resisting material slidably fitted to the rear end of the casing and handle in such a way as to close from the exterior a cavity in direct communication with the inner surface of the sole plate the temperature of which is to be controlled, screw clamps on the said insulating plate for securing current-supply wires, a support made of electrically insulating and heat-resisting material freely disposed at the rear end of the soleplate, electrical heating elements freely embedded in the grooves formed in the sole-plate, spring terminal clamps on the insulating support, the heating elements being connected with the said spring terminal clamps, contact brushes on the lower edge of the insulating plate adapted to bear against the spring terminal clamps on the insulating support, conducting means connecting the screw clamps with the contact brushes to transmit current through the spring clamps to the heating circuits, and a tempmature-regulating device mounted on the inner face of the insulating plate.

2. A pressing iron as claimed in claim 1, the casing and the handle being made of a thermo-setting synthetic resin, and the pressing iron further comprising a body of solid heat-resisting thermally and electrically insulating ma terial, such as porous cement, interposed between the casing and the sole-plate, and fully insulating the casing and handle thermally from the sole-plate.

3. A pressing iron as claimed in claim 1, wherein two distinct heating elements fully independent of one another are freely embedded in the grooves provided in the inner surface of the sole-plate, the pressing iron further comprising a plug adapted for connecting the two heating elements alternatively in series or in parallel with one another as required, and the temperature regulating device being a single thermo-stat, including a bi-metallic member, adapted to regulate the temperature of the two heating elements either in series or in parallel with one another, and capable of effecting an instantaneous make and break of the heating circuit.

4. A pressing iron as claimed in claim 3, the plug for the alternative series and parallel connection of the two heating elements, adapted to be inserted with its plug pins in either of two positions by displacing the two pins through an angle of degrees, one of the said positions establishing the series connection of the two heating elements and the other position establishing the parallel connection, the plug also embodying a safety fuse inserted in the parallel connection, this fuse being readily exchangeable from the exterior by merely unscrewing a plug pin.

5. A pressing iron, comprising: a sole-plate, heating elements disposed on the inner face of the sole-plate, a heat-resisting and electrically insulating support freely disposed on the rear end of the sole-plate, spring terminal clamps lodged in the said support and movable up and down therein, the ends of the heating elements being clamped thereto, a body of heat-resisting and electrically insulating material disposed on the sole-plate above the heating elements, a casing and handle of synthetic resin material disposed on the said body, an approximately upright plate of heat-resisting and electrically insulating material applied to the rear of the casing and handle so as to enclose between itself and them a cavity which is open at the bottom to the sole-plate, screw clamps on the outside of the said insulating plate for connection to current-supply conductors, contact brushes on the lower edge of the insulating plate adapted to bear conductively on the spring terminal clamps, and conductors adapted to conduct current from the screw clamps of the current supply to the said contact brushes.

6. A pressing iron, comprising: a sole-plate formed with grooves in its inner surface, a casing, including a handle, mounted upon the sole-plate, a substantially upright plate of electrically insulating and heat-resisting material fitted to the rear end of the casing and handle, three screw clamps mounted on the outside of the insulating plate for securing current-supply wires, two electrical heating elements disposed in the grooves provided in the inner surface of the sole-plate, a support made of electrically insulating and heat-resisting material freely disposed at the rear end of the sole-plate, four spring terminal clamps on the insulating support, the ends of the two heating elements being severally connected to the said spring terminal clamps, four contact brushes on the lower edge of the insulating plate, each adapted to bear against one of the said spring terminal clamps, conducting means permanently connecting two of the screw clamps separately with two of the contact brushes, namely one asociated with each of the heating elements, conducting means capable of connecting the third screw clamp with both the remaining contact brushes, and a current plug adapted to connect the two heating elements in series with one another by applying voltage across the two permanently connected screw clamps only, or alternatively in parallel with one another by connecting the two permanently connected screw clamps with one another and applying voltage across this connection and the third screw clamp.

7. A pressing iron as claimed in claim 6, further comprising: a conducting disc mounted on the insulating plate and conductively connected with the third screw clamp, a bi-metallic member secured by one end to the insulating plate, a swinging plate pivotally mounted on the insulating plate, a tension spring connecting the free end of the pivoted plate to the free end of the bi-metallic member, the points of connection of the spring being such that the spring tends to draw the swinging plate towards or away from the conducting disc according as the point of connection of the spring to the bi-metallic member is nearer to or farther from the plane of the conducting disc than the pivotal axis of the swinging plate, and two contacts, each connected with one of the heating elements through one of its spring clamps and one of the brushes, these two contacts being so mounted on the swinging plate as to be brought into and out of contact with the conducting disc according as the swinging plate is moved towards or away from the said disc.

8. A pressing iron, comprising: a sole-plate, formed with grooves in its inner surface capable of accommodating two heating elements side by side and fully independent of one another, a casing, including a handle, of synthetic resin material, mounted upon the sole-plate, a plate of electrically insulating and heat-resisting material fitted to the rear end of the casing and handle so as to enclose in conjunction therewith, in a fluid-tight manner, a cavity in communication with the inner surface of the sole-plate the temperature of which is to be controlled, screw clamps on the said insulating plate for securing current-supply wires, a support made of electrically insulating and heatresisting material freely disposed on the rear end of the sole-plate, two electrical heating elements fully independent of one another embedded in the grooves formed in the sole-plate, spring terminal clamps on the insulating support freely lodged therein and movable up and down, the heating elements being connected with the said spring terminal clamps, a body of thermally insulating, heatresisting and electrically insulating material disposed on the sole-plate above the heating elements, contact brushes on the lower edge of the insulating plate adapted to bear against the spring terminal clamps on the insulating support, conducting means connecting the screw clamps with the contact brushes to transmit current through the spring clamps to the heating elements, and a temperature-regulating device mounted on the inner surface of the insulating plate.

References Cited in the file of this patent UNITED STATES PATENTS 61,198 Hood Jan. 15, 1867 1,370,916 Russell Mar. 8, 1921 1,391,167 Carlson Sept. 20, 1921 1,437,111 Lamb Nov. 28, 1922 1,534,542 Reimers et a1. Apr. 21, 1925 1,678,310 Woodrufi July 24, 1928 2,024,471 Norton Dec. 17, 1935 2,323,162 Talmage June 29, 1943 2,357,905 Olving Sept. 12, 1944 2,373,248 Lucia Apr. 10, 1945 2,512,062 Huffman June 20, 1950 FOREIGN PATENTS 656,017 France Dec. 24. 1928 

